`SIMON` NEW `ODD COUPLE` OF TV SHOWS

Steve DaleCHICAGO TRIBUNE

''The answer is very simple,'' says executive producer Philip DeGuere explaining his theory for the success of ''Simon & Simon,'' the CBS series that he created. ''The characters (brothers A.J. and Rick Simon) are believable, likable and, most important, they care about one another.''

Whether or not that`s the reason viewers turn on ''Simon & Simon'' at 8 p.m. Thursdays on CBS-Ch. 2, it`s obvious they love the detective series. For the last three years, it has finished in the top 10 prime-time shows, according to A.C. Nielsen Co.

friendship,'' explains Parker, who recently appeared in a play near Chicago.

''Similarly, our relationship could never be split because we`re brothers.''

Parker`s A.J. is the Felix-type of the ''Simon'' team--he`s always impeccably dressed. He captures thieves while wearing three-piece suits and never seems ruffled. Brother Rick is played by Gerald McRaney, the Oscar-like half, who prefers tattered blue jeans and cowboy boots. Rick loves chasing women and downing beers.

''We wanted a contradictory relationship between principals, two hostile personalities,'' says DeGuere by telephone from Los Angeles. ''But we needed a reason to keep them working with each other. That`s why we made them brothers.''

''Simon'' began as a pilot called ''Private`s Key'' set on a mythical island in the Florida Keys. Instead, CBS opted for another new ''island'' show called ''Magnum, P.I.''

''It was a blessing in disguise,'' says DeGuere, currently working on a remake of ''The Twilight Zone,'' which will premiere on CBS this fall. ''We had a whole year to work on the second pilot. Most programs are rushed on the air in a matter of weeks. We had the time to fine-tune, to really prepare.''

The show was renamed ''Simon & Simon'' and the location moved to San Diego. A second pilot didn`t rate much better, but the network decided to give the series a try and in 1981 scheduled it for 7 p.m. on Tuesdays.

It finished in 70th place that season. Even Parker, who says that he`s too busy acting to pay attention to ratings points says, ''I never thought we`d have a second season.''

''Simon'' was almost yanked from the CBS schedule, but a network executive had faith, and in a last-ditch effort during the 1982-83 season, the show was moved to 8 p.m. Thursdays, following the popular ''Magnum, P.I.''

series. The gamble worked. The strong lead-in from ''Magnum'' helped ''Simon'' gain viewers. In fact, it was the seventh ranked show that season. Last season, ''Simon'' also finished in seventh place, down two spots from the previous year. Ironically, the series is doing better than ''Magnum,'' which slipped to 15th place last season from 6th place the year before.

Parker recently talked about his series while waiting to appear in ''Cat on a Hot Tin Roof'' at his alma mater, Beloit College in Beloit, Wis. ''The characters themselves make it work,'' said Parker. ''Rick and A.J. are very human. They`re also very American. They both drive American cars, probably eat apple pie and love their mother.''

Their mother is played by Mary Carver, who regularly reduces her big, tough on-screen sons to Jell-O. ''That`s the charm,'' adds Parker, looking younger than his 37 years.

Parker lives in Los Angeles with his wife, Bonnie, a part-time actress and photographer, and their two children, Francis, 6, and Christian, 2. He drives a pick-up truck, hates Hollywood parties and describes himself as being shy. He hopes to move to Vermont or West Virginia one day.

Though ''Simon'' is a hit, Parker doesn`t exactly get the star treatment when he steps out. ''People don`t know know who I am,'' he laughs. ''They get me confused with Parker Stevenson or `Mackie,` '' his nickname for McRaney.

Parker, a native of Baltimore, enrolled at Beloit in 1968 after being expelled from an Eastern high school boarding school two weeks before graduation due to what he terms ''a series of errors in judgment. The headmaster didn`t have a sense of humor,'' says Parker. ''When I brought a cow into a classmate`s room, the headmaster had enough of my pranks.''

Though he applied to Ivy League schools, only Beloit and the University of Pennsylvania accepted him after his high school expulsion.

''I chose Beloit because it was small,'' he says.

After graduation in 1971 from Beloit, where he studied drama, Parker went to New York and performed in several off-Broadway productions before joining the daytime soap, ''One Life to Live.'' His motion picture credits include

''The Bell Jar'' (1979) and ''A Small Circle of Friends'' (1980). He also has done TV movies and had guest appearances on the TV series ''Family'' and

''Hart to Hart.''

Parker has concerns about next season`s ''Simon & Simon.'' ''They`re

(writers and producers) beginning to put too much emphasis on car chases and shooting, instead of the characters. Special effects and heroics won`t win us viewers. Between us, Mackie and I have 35 years in the business, I think we`ve learned something. There`s a mutual respect on our show. I think the writers and producers will listen to us.''

Parker adds that he hopes to see a more prominent role for ''Simon''

character Downtown Brown, played by Tim Reid, former Chicago comic and known as Venus Flytrap on ''WKRP in Cincinnati.''

Parker just completed co-producing a feature film called ''Jackal'' with actor Jack Lucarelli, who also stars. McRaney plays a sadistic villain in the film, which might be released in November.

''I`m not interested in directing,'' he says. ''I do enjoy producing though, and I`ll continue acting as long as I can. But let`s face it, how many actors have true television longevity? James Garner, Robert Wagner, and that`s about it. The experience at producing is my insurance policy.